Various methods are known for drying, for example, objects to be washed in a dishwasher. For example, the objects to be washed can be dried by own-heat drying if the rinsing liquid is heated in a partial programme step “clear rinse” and thus the objects to be washed which have undergone a hot clear rinse are dried by themselves by the self-heat of the objects to be washed which has thus built up during the drying process. In order to achieve this own-heat drying, the rinsing liquid is heated to a certain temperature in a heat exchanger in the “clear rinse” partial programme step and applied to the objects to be washed by means of spraying devices. As a result of the relatively high temperature of the rinsing liquid in the “clear rinse” partial programme step of usually 65° C. to 75° C., it is achieved that a sufficiently large quantity of heat is transferred to the objects to be washed so that water adhering to said objects to be washed vaporises as a result of the heat stored in the objects to the washed.
In a further known methods for drying the objects to be washed in dishwashers, a separate heat source, e.g. a hot air fan, is used to heat the moist air mixture during the drying process so that the air in the washing basket can absorb a larger quantity of moisture.
Dishwashers are known in which the moist air is vented outwards. This is disadvantageous since the surrounding kitchen furniture is damaged.
Thus, further methods are known in which the moist air is passed over condensing surfaces on which the moisture condenses before being guided out. This condensation is either passed into the washing basket or into special collecting containers.
A method of the type specified initially for dishwashers is known from DE 20 16 831 wherein the air from the washing container is guiding via a closable opening in the wall of the washing container onto reversibly dehydratable material and from there outwards via an opening. The desorption of the reversibly dehydratable material takes place during the standstill phase of the appliance wherein the water vapour produced is guided outwards again via the opening. As has already been explained above, this is disadvantageous since the surrounding kitchen furniture is damaged.
A disadvantage in the heating systems described above according to the prior art described further above is that the heating of the rinsing liquid is associated with a high energy requirement and the thermal energy required for each heating phase must be produced anew by means of electrical heating elements. The known heating systems also have the disadvantage that the heating of the rinsing liquid in the “clear rinse” partial programme step and the processes in the “drying” partial programme step are themselves associated with a high energy requirement and the thermal energy required is lost after the drying process.